Though unillustrated, a conventional precision substrate storage container is composed of a container body for storing multiple semiconductor wafers in alignment, a door component for opening and closing the container body and a bottom plate attached to the bottom surface of the container body.
The container body has a front-open box configuration having an opening in the front and a multiple number of paired supporting ribs arranged vertically on the interior walls on both sides for supporting semiconductor wafers horizontally. Formed on the interior periphery on the front side are a multiple number of engaging holes. The door component incorporates a latching mechanism which, by control from the outside, fits retractable engaging claws into the engaging holes.
In the above configuration, when multiple semiconductor wafers are processed, the precision substrate storage container, together with an empty in-process container or an open cassette, is set and positioned onto the carrier stage of handling equipment, first.
Thereupon, the latching mechanism of the door component is unlocked, the door component for securing airtightness is removed from the front of the container body to open the container body. As the container body is opened in this way, multiple semiconductor wafers are checked as to their storage state and taken out one by one from the lowermost by means of a transfer device of the handling equipment and brought, one by one, into an empty in-process container or open cassette from the bottom. Thereafter the wafers will be subjected to predetermined processes.
Upon processing and fabrication of semiconductor wafers, it is necessary to exactly discriminate and identify the type of the semiconductor wafers and the information as to the precision substrate storage container etc. In order to make such identification, conventionally, a production system using a non-contact type communication device has been established, and a technique for providing a pocket for a transponder of a non-contact type communication type in the precision substrate storage container has been proposed (Japanese Patent Application Laid-open 2000-21966). There is also another disclosure of a technique whereby a holder groove is formed at one end part of a transport carrier of semiconductor wafers and a transponder or the like is accommodated in the holder groove and the opening is enclosed (Japanese Patent No. 2651357).
In the prior art, the type of semiconductor wafers and the information as to the precision substrate storage container etc., are discriminated and identified in the above ways, however, these techniques entail the following problems.
First, in ether case of the above patent literatures, since the transponder is oriented to one direction only, communication failure is liable to take place even if an identical transponder is used, depending on the setup specification of the communication area on the equipment side; this is a big problem. Generally, a typical transponder is given in a cylindrical form, which is prone to induce setting in a wrong direction. Wrong directivity degrades information transfer performance and may cause difference in information transmission function during use even if transponders and precision substrate storage containers of the same kinds are used.
Detail of this problem will be described taking an example of a production system using a typical RFID. Generally, a RFID system includes a host computer, an interrogator (reader/writer) and a transponder (IC tag). The interrogator is composed of a controller, a transmitter/receiver and an antenna, and exchanges information with the host computer under its control. This interrogator has the functions of reading and checking the information from the transponder and writing information into it, and is mounted in the equipment handling the precision substrate storage containers and predetermined equipment in the process. The transponder is composed of an antenna, a transmitter/receiver and a memory, and is mounted in the precision substrate storage container and records the semiconductor wafers' lot, in-process fabrication or work progress in the process.
The production system of this kind may use various transmission systems such as an electromagnetic coupling system, electrostatic coupling system, microwave system, optical communication system or the like, and specifications including the communication distance, storage capacity, environment resistance and others should be designated depending on the selected system.
Meanwhile, system configurations have not been unified in different plants handling precision substrate storage containers while the position and direction for transmitting and receiving transmission signals are diverse between different equipment units. As a result, if a precision substrate storage container with RFID, which has functioned correctly at a certain plant, is attempted to be used in another plant or another process, there is more than a little possibility of information exchange becoming difficult or impossible.
Further, since the usable frequency for the reading/writing area is different depending on the country, if a precision substrate storage container is used abroad, the precision substrate storage container should be configured so as to be usable inside and outside the country, or it is necessary to severely manage and discriminate the products for domestic use and overseas use.
Furthermore, though the transponder of the system is communicable even if it is more or less deviated from the front of the interrogator, the reading area becomes smaller by 20 to 30% as its relative position to the interrogator changes 90 degrees, therefore there is a fear of communication errors occurring due to its position relative to the interrogator. Accordingly, there is demand for a universal precision substrate storage container with a built-in transponder, which can support any system and has interchangeability between plants and between equipment units. However, if the reading area is enlarged so as to solve the above problem, there occurs a new problem in that the contents from other adjacent transponders residing nearby may be erroneously picked up.